Aug. 18, 19*3 
Sulphur Compounds in Dry Lime-Sulphur 
331 
The data given in the Tables II and III show that the results secured 
for the different forms of sulphur—residual, thiosulphate, and monosul- 
phid—are quite concordant, whether the length of time of the experi¬ 
ment was one hour or a longer period. The use of hydrated Na^, 3.6 
and 4.7 normal NaOH, and NH 4 OH also served satisfactorily as absorp¬ 
tion solutions. Further experiments with iodin were not as satisfactory. 
Further evidence of the completeness of the action of carbonic acid 
is borne out by a comparison with the results obtained by the use of hydro¬ 
chloric acid. Five-tenths gm. of dry lime-sulphur from the same sample 
used in establishing the proposed methods was transferred to the reaction 
flask, A, dry and oxygen-free C( 3 2 passed through the apparatus, a suffi¬ 
cient quantity of distilled water added to cover the ends of the inlet 
tubes, and, finally, 8.36 cc. of N/2 HC 1 , an amount previously found 
necessary to neutralize the basicity of the solution, were slowly added to 
the sulphid in solution. All traces of acid adhering to the separatory 
funnel were removed by rinsing with water containing a few drops of 
methyl orange. That the quantity of acid added was sufficient was in¬ 
dicated by a faint pink coloration of the solution. The contents of the 
flask were agitated during and after the admission of the acid, and C 0 2 
was passed through the solution for a period of hours. 
The results obtained upon analysis of the three forms of sulphur are 
as follows: 
Residual sulphur. 50. 96 per cent. 
Thiosulphate sulphur. 2. 48 per cent. 
Monosulphid sulphur. 8.47 per cent. 
Another experiment was made, using the same weight of dry lime- 
sulphur from the same sample but increasing the amount of N/ 2 HC 1 to 
a large excess over that actually required and substituting pure nitrogen 
gas in place of C0 2 . The solution in this case was brought to the boiling 
point near the end of the operation. The results obtained are as follows: 
Residual sulphur. 51*56 per cent. 
Monosulphid sulphur. 8. 35 per cent. 
The percentage results obtained for monosulphid sulphur in these 
two experiments are in close agreement with the results obtained by the 
use of the carbonic-acid method. The slight increase in the percent¬ 
age of residual sulphur is due to the action of HC 1 upon the thiosul¬ 
phate in solution which causes a precipitation of sulphur. 
DETERMINATION OF MONOSULPHID AND THIOSULPHATE SULPHUR 
AFTER A PREVIOUS SEPARATION OF SULPHID FRQM THIOSULPHATE 
The accuracy of the monosulphid and thiosulphate sulphur results as 
determined by the carbonic-acid method was again established by the 
following experimental work in which the same sample of dry lime- 
sulphur was used. 
Five-tenths gm. of dry lime-sulphur was transferred to a small Erlen- 
meyer flask, to which was quickly added an excess of freshly prepared 
and well-washed ZnC 0 3 held in water suspension. The flask was imme¬ 
diately stoppered and shaken vigorously, and the shaking repeated at 
intervals during a period of one hour, after which the ZnS mixed with 
free S and excess ZnC 0 3 was filtered and washed free from the thiosul¬ 
phate in solution. The thiosulphate sulphur, which was found to equal 
2.65 per cent, was determined by titrating the filtrate with Nf20 iodin. 
